Question: $\left(-8x + 4\right)\left(x - 9\right) = \ ?$
Answer: $= -8x \cdot \left(x - 9\right) + 4 \cdot \left(x - 9\right)$ $= \left( -8x \cdot x \right) + \left( -8x \cdot -9 \right) + \left( 4 \cdot x \right) + \left( 4 \cdot -9 \right)$ $= -8x^2 + \left( -8x \cdot -9 \right) + \left( 4 \cdot x \right) + \left( 4 \cdot -9 \right)$ $= -8x^2 + \left( 72x + 4x \right) + \left( 4 \cdot -9 \right)$ $= -8x^2 + 76x + \left( 4 \cdot -9 \right)$ $= -8x^2 + 76x - 36$